`ToTensor()` transform adds unexpected dim

[Nic-Ma]

Describe the bug
A bug reported by Hogler:
When using ToTensor() transform on a numpy array with 0 dims, it added 1 dim.
The root cause is np.ascontiguousarray() added a dim:

>>> a = np.ascontiguousarray(2)
>>> 
>>> print(a)
[2]

I will try to fix it ASAP.

Thanks.